Big Cheese clone Oscillation

[billyblunt]

Hi guys, I've just built a Big Cheese clone using the feta complis schematic. I'm getting some heavy oscillation once the tone knob is more than 50%. Its worse if the tone pot on the guitar is maxed out, makes it unusable. I've checked & rechecked everything & nothing obvious is jumping out at me. Could it be simply poor placement?

[midwayfair]

1) Move around your off-board wires and see if that changes anything.
2) Make sure nothing's microphonic, especially if you used any ceramic caps. Tapping on the PCB with a chopstick works for me.
3) Audio probe and see where it's introduced.
4) Try putting a buffer in front -- if this helps I might have some other suggestions for the root of the problem.

[billyblunt]

Thanks for the suggestions, I shall give them all a try.

[m-Kresol]

Did you solve your problem yet?
Did you sub the 2n3904 for BC549C as suggested by lacesensor in our GB thread? If yes, did you turn them 180°? The pinout of the BC549C is the opposite of the 2n3904...

[luks999]

the big cheese already has a buffer at the beginning and at the end (to my knowledge)
im curious how your debugging goes on

[Morgan]

I built one a few years back on the OLC pcb. I used shielded wires running from the jacks to the footswitch to squelch oscillation.